1. Field of the Invention
The present invention relates to network systems, and more particularly, to a network system for executing automatic distribution processing of network management information and monitoring processing of network units.
2. Description of the Related Art
As the Internet has been widely used, networks have been made at various places. Then, it is demanded that each network be managed efficiently.
As a protocol for monitoring units connected to a network, Simple Network Management Protocol (SNMP), Common Management Information Protocol (CMIP), Transaction Language 1 (TL1), Hypertext Transfer Protocol (HTTP), or a vendor-unique protocol is used. A SNMP management method will be described below as an example.
SNMP is formed of an agent (SNMP agent) residing in a management-target unit (client or network-information management server) and a manager (SNMP manager) residing in a managing unit (monitoring server). Information exchanged between the SNMP manager and the SNMP agent is divided into three classes: requests and acknowledgements for information acquisition (Get command), requests and acknowledgements for information setting (Set command), and status-change notices (trap).
With a Get command, the SNMP manager requests the SNMP agent to obtain information. The SNMP agent refers to a management information base (MIB) to obtain information and sends it back to the SNMP manager. With a Set command, the SNMP manager requests the SNMP agent to perform setting. The SNMP agent changes MIB information and sends the result back to the SNMP manager. The SNMP agent sends a trap to the SNMP manager to report a change in status of the SNMP agent.
To perform communication with SNMP, it is necessary to specify a source IP, a community name, an MIB access right, a trap notice setting, and others in the SNMP agent. The source IP is usually set to the IP address of the SNMP manager, and is used as the destination of a trap sent from the SNMP agent to the SNMP manager. The community name is used for authentication between the SNMP manager and the SNMP agent. When the SNMP manager sends a Get or Set command by the SNMP packet to the SNMP agent, the SNMP manager stores the community name in the SNMP packet. The SNMP agent checks the community name, and, when the community name is an authorized community name, the SNMP agent executes an operation (such as that specified by a Get or Set command) permitted for the community name. The MIB access right is a right for the SNMP manager to access the MIB of the SNMP agent. The trap notice setting specifies whether the SNMP agent can send a trap. SNMP is described in RFC 1157.
As a method for automating network setting of units connected to a network, Dynamic Host Configuration Protocol (DHCP) or Bootstrap Protocol (BOOTP) is used. DHCP will be described here as an example.
With DHCP, information is exchanged between a unit (DHCP client) that receives setting information and a server (DHCP server) that manages setting information in a unified manner and assigns information to the DHCP client. When the DHCP server receives a network setting request from the DHCP client, the DHCP server sends information, such as an IP address, a net mask, and a default gateway to the DHCP client. DHCP is described in RFC 2131.
A technology for automatically obtaining network management information by the use of a combination of DHCP and TFTP has also been used (see non-patent document 3). When the DHCP server receives a network setting request, the DHCP server sends to the DHCP client, the IP address of a TFTP server and a file storage place from which downloading is to be executed. When the DHCP client finishes setting the IP address, the DHCP client downloads network management information from the TFTP server according to the information sent from the DHCP server.    Non-patent document 1: RFC 1157    Non-patent document 2: RFC 2131    Non-patent document 3: RFC 783 (TFTP), RFC 2131 (DHCP), http://www.cisco.com/japanese/warp/public/3/jp/service/manual—j/sw/cat30/3550 mscg/chapter04/04_swipaddr.html#18750 (Cisco URL information)